Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Osteoblasts-Derived Exosomes as Potential Novel Communicators in Particle-Induced Periprosthetic Osteolysis(Elsevier, 2024) de Souza, Wanderson; Gemini-Piperni, S.; Ruivo, Carolina; Bastos, Nuno; Almeida, Sofia; Lopes, Daniel; Ribeiro, Ana R.The inflammatory response to wear particles derived from hip prothesis is considered a hallmark of periprosthetic osteolysis, which can ultimately lead to the need for revision surgery. Exosomes (Exos) have been associated with various bone pathologies, and there is increasing recognition in the literature that they actively transport molecules throughout the body. The role of wear particles in osteoblast-derived Exos is unknown, and the potential contribution of Exos to osteoimmune communication and periprosthetic osteolysis niche is still in its infancy. Given this, we investigate how titanium dioxide nanoparticles (TiO2 NPs), similar in size and composition to prosthetic wear particles, affect Exos biogenesis. Two osteoblastic cell models commonly used to study the response of osteoblasts to wear particles were selected as a proof of concept. The contribution of Exos to periprosthetic osteolysis was assessed by functional assays in which primary human macrophages were stimulated with bone-derived Exos. We demonstrated that TiO2 NPs enter multivesicular bodies, the nascent of Exos, altering osteoblast-derived Exos secretion and molecular cargo. No significant differences were observed in Exos morphology and size. However, functional assays reveal that Exos cargo enriched in uPA stimulates macrophages to a mixed M1 and M2 phenotype, inducing the release of pro- and anti-inflammatory signals characteristic of periprosthetic osteolysis. In addition, we demonstrated the expression of uPA in exosomes derived from the urine of patients with osteolysis. These results suggest that uPA can be a potential biomarker of osteolysis. In the future, uPa may serve as a possible non-invasive biomarker to identify patients at risk for peri-implant osteolysis.Article Citation - WoS: 5Citation - Scopus: 6Formation of Monolithic Srtio3-Tio2 Ceramic Heterostructures by Reactive Hydrothermal Sintering(Elsevier, 2023) Karacasulu, Levent; Kartal, Uğur; İçin, Öykü; Bortolotti, Mauro; Biesuz, Mattia; Ahmetoğlu, Çekdar VakıfIn a one-pot approach, monolithic SrTiO3-TiO2 ceramic heterostructures were obtained using the reactive hydrothermal liquid phase densification (rHLPD). Structural, morphological, and photocatalytic properties of the obtained ceramics were analyzed. The relative density of the formed components reached about 80% with reaction time, temperature, and NaOH concentration variation. It was observed via Rietveld refinement that there was no XRD detectable phase other than TiO2 and SrTiO3 in the final structure. The monolithic SrTiO3-TiO2 ceramics obtained by hydrothermal reaction at 120 °C for 24 h in 1 M NaOH concentration showed a dielectric constant being around 500, and the dielectric loss was below 0.25 at frequencies higher than 10 kHz. The SrTiO3-TiO2 heterostructured monoliths having only 20 vol% total porosity and low specific surface area, demonstrated ∼60% efficiency (in 5 h) in degrading Methylene Blue photo-catalytically. © 2023 Elsevier LtdArticle Citation - WoS: 103Citation - Scopus: 113Preparation and Characterizations of Tio2/Zno Nanohybrid and Its Application in Photocatalytic Degradation of Tetracycline in Wastewater(Elsevier, 2023) Zeinali Heris, Saeed; Etemadi, Martin; Mousavi, Seyed Borhan; Mohammadpourfard, Mousa; Ramavandi, BahmanThe photodegradation of tetracycline antibiotics (TC) in an aqueous solution, using the TiO2 nanoparticles, ZnO microparticles, and TiO2/ZnO composite under the UV lamp in a continuous reactor, was performed. The effects of different parameters, such as the initial TC concentration, medium pH, ratio of each photocatalyst, and the flow rate were comprehensively studied. SEM, EDX, and XRD characterization techniques were employed to study the morphology and structure features of the prepared composite. The results revealed that a more significant amount of TC is not easily removed from wastewater. Furthermore, by increasing the pH of the medium to 11, the efficiency of TC degradation was increased, while the amount of removal remained stable at higher pH values. As the flow rate increased up to 190 mL/min, the removal efficiency increased; however, at higher flow rates, lower efficiency was obtained. Moreover, using multivariate analysis and response surface methodology (RSM), a model for removing TC and the effect of experimental parameters on removal efficiency was proposed. The optimal conditions using the RSM method were found to be the reduction efficiency of 78.94 % in pH = 11 (flow rate of 132 mL/min, and TiO2 concentration of 323 mg) and reduction efficiency of 75.89% in pH = 9 (flow rate of 143.19 mL/min and TiO2 concentration of 312.73 mg). © 2023 Elsevier B.V.Article Citation - WoS: 8Citation - Scopus: 8Crystallization and Additional Oxide Interlayers Improve the Tribocorrosion Resistance of Tio2 Nanotubular Surfaces Formed on Ti6al4v(Elsevier, 2023) Çaha, İhsan; Türü, İrem Cemre; Erdoğan, Ece; Pinto, Ana Maria Pires; Cansever, Nurhan; Deepak, Francis Leonard; Toptan, Fatih; Alves, Alexandra C.TiO2-based nanotubular surfaces have promising properties for various industrial applications, such as solar cells, fuel cells, photocatalysis, energy storage, gas sensors, and biomedical applications. However, they have very limited use in real applications, and one of the major limiting factors is the weak adhesion of nanotubular surfaces to the substrate. In this study, nanotubular surfaces are formed on Ti6Al4V alloy by anodic treatment followed by a heat treatment at 500 °C for 3 h under an open atmosphere. Microstructural investigations revealed self-organized nanotubes grown on both ? and ? phases. High-resolution TEM/STEM analysis showed crystallization of the nanotubular layer and formation of additional oxide interlayers resulting in a drastic improvement in tribocorrosion resistance. These findings indicated that a simple heat treatment can significantly alter the properties of nanotubular layers and can widen their usage mainly for load-bearing implant applications in corrosive environments. © 2023 Elsevier B.V.Article Citation - WoS: 4Citation - Scopus: 5The Effect of Geometrical Characteristics of Tio2 Nanotube Arrays on the Photocatalytic Degradation of Organic Pollutants(Springer, 2023) Kartal, Uğur; Uzunbayır, Begüm; Doluel, Eyyüp Can; Yurddaşkal, Metin; Erol, MustafaHighly ordered TiO2 nanotube arrays (TNAs) were fabricated by electrochemical anodization under varying durations and voltages. The effects of the anodizing parameters on geometrical properties were investigated. The results showed that as the anodizing time increased from 15 to 45 min, the length of the nanotubes increased, but there was no change in their diameter, hence the surface area increased while the open porosity did not change. When the effect of the anodizing voltage was examined, it was observed that both the length and diameter increased as the voltage increased from 15 to 45 V. Thus, a significant increase in open porosity and surface area was observed. The UV-Vis spectrophotometer was used to evaluate the effects of all geometrical characteristics on the photodegradation of methylene blue (MB). The results showed that the anodizing parameters were highly effective on the photocatalytic degradation of MB. With the decrease of the anodizing voltage, the photocatalytic activity increased because of the geometrical characteristics of TNAs. Accordingly, TNAs with the surface area of 25 m(2)/g and the open porosity of 35% obtained by anodizing for 45 min at 15 V showed the highest photocatalytic activity with a degradation efficiency of similar to 81% in 7 h.Article Citation - WoS: 24Citation - Scopus: 27Atomic–scale Investigations of Passive Film Formation on Ti-Nb Alloys(Elsevier, 2023) Çaha, İhsan; Alves, Alexandra C.; Chirico, Caterina; Maria Pinto, Ana; Tsipas, Sophia; Gordo, Elena; Bondarchuk, Oleksandr; Leonard Deepak, Francis; Toptan, FatihThis study extensively investigates the passive film formation mechanisms on Ti-xNb alloys by using several electrochemical techniques, including electrochemical impedance spectroscopy (EIS) before and after potentiostatic polarization at the passive zone, and Mott-Schottky (MS) measurements in 9 g/l NaCl electrolyte at 37 °C, together with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis. Overall, the Ti40Nb presented lower corrosion resistance due to a thinner passive film as compared to commercial pure Ti (grade 2) and Ti12Nb. The passive film formed on Ti12Nb and Ti40Nb alloys at a steady-state condition (+0.5 VAg/AgCl for 60 min) is composed of amorphous phases of TiO, Ti2O3, TiO2, Nb2O5 and crystalline phases of TiO2 (anatase) and Nb2O5. © 2022 Elsevier B.V.Article Citation - WoS: 6Citation - Scopus: 6Photocatalytic Activity of Dye-Sensitized and Non-Sensitized Go-Tio2 Nanocomposites Under Simulated and Direct Sunlight(Wiley-Blackwell, 2022) İlhan, Hatice; Durmaz Çaycı, Gamze Belkis; Aksoy, Erkan; Diker, Halide; Varlıklı, CananGraphene oxide (GO), amine-modified graphene oxide (mGO), and N-TiO2 composites were synthesized by low-temperature hydrothermal method and characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, FTIR, and BET analysis techniques. The films of synthesized TiO2, mGO:TiO2, N-TiO2, GO:TiO2, GO:N-TiO2, and commercially available P25 were prepared by doctor blade method. These films and their perylene-3,4,9,10-tetracarboxy tetrabutylester (PTE)-sensitized forms were employed as photocatalysts for the photodegradation of rhodamine-B (RhB) under Xe lamp and direct sunlight irradiations. Independent from the irradiation source, the photocatalytic order of the non-sensitized films were GO:N-TiO2 > GO:TiO2 > N-TiO2 > mGO:TiO2 > TiO2 > P25, but seven and 15 folds of increments were detected under direct sunlight irradiation. PTE-sensitized catalyst films exhibited more than two folds of increase in the photocatalytic rate constants compared to their non-sensitized counterparts under Xe lamp irradiation. Under direct sunlight irradiation no matter which photocatalyst was used, the photocatalytic activity of these films was enhanced seven folds. Reusability tests revealed no significant changes in the photocatalytic rate constants obtained with both the non-sensitized and sensitized films.Article Citation - WoS: 1Citation - Scopus: 1Substrate Effects on Electrical Parameters of Dirac Fermions in Graphene(Elsevier, 2021) Tıraş, Engin; Ardalı, Şükrü; Fırat, Hakan Asaf; Arslan, Engin; Özbay, EkmelThe substrate effects on the electronic transport properties of single-layer graphene on TiO2/Si substrate have been studied. The Hall mobility, sheet carrier density, and transport lifetime were obtained from the temperature-dependent Hall measurements, while the in-plane effective mass, quantum lifetime was obtained from the temperature-dependent variation of the Shubnikov de Haas (SdH) oscillations that were made at 1.8 to 45 K temperature range and up to the magnetic field of 11 T. The measurement results showed that in SLG/TiO2/ Si sample, there were 2.36 +/- 0.12x1016 m-3 amounts of 3D carriers coming from the substrate. In our previous studies, 3D carrier densities were measured as 6.07x1016 m-3 and zero for SLG/SiO2/Si and SLG/SiC sample, respectively. This result shows that the 3D carriers formed in the structure are significantly changed by a substrate. The scattering mechanisms were determined using the zt/zq ratio. The ratio values obtained as 3.66. This value obtained was compared with the values we found for SLG/SiC (zt/zq=1.36) sample and SLG/TiO2/Si (zt/zq=3.08) sample our previous study. The results show that small-angle scattering is dominant in SLG/SiC sample, but large-angle scattering is dominant in SLG/SiO2/Si and SLG/TiO2/Si samples. The charged impurity scattering is the dominant scattering mechanism in SLG/TiO2/Si and SLG/SiO2/Si samples, whereas in SLG/SiC samples, a short-range scattering mechanism such as lattice defects can be said to affect the electronic transport.Article Citation - WoS: 12Citation - Scopus: 12Dye Removal by Polymer Derived Ceramic Nanobeads(Elsevier, 2021) İçin, Öykü; Ahmetoğlu, Çekdar VakıfEmulsion processed polymer derived ceramic (PDC) nanobeads are used for Methylene Blue dye removal from aqueous solutions. The PDC nanobeads, produced at 600 degrees C and 1200 degrees C pyrolysis, are subsequently coated with titania (anatase). Titania-coated nanobeads show less than 35%, i.e., limited dye adsorption capability in dark. Instead, enhanced total removal efficiency (similar to 97%) is obtained when the initial adsorption is succeeded by photodegradation under UV. Direct reusability tests show that even after the third cycle, very high regeneration efficiencies being above 92% are observed for titania-coated nanobeads.Article Citation - WoS: 19Citation - Scopus: 22Enhanced Methylene Blue Removal Efficiency of Tio2 Embedded Porous Glass(Elsevier Ltd., 2021) Ertuş, E.Burak; Vakıfahmetoğlu, Çekdar; Öztürk, AbdullahA porous glass (PG) embedded with titanium dioxide (TiO2) was produced via impregnation of the PG with Titanium (IV) Isopropoxide solution followed by crystallization. N2 sorption analyses revealed that the specific surface area (SSA) and total pore volume of the PG reached to 358 m2/g and 0.370 cm3/g, respectively. The adsorption capacity of methylene blue (MB) for the glasses was measured in the dark, instead the photocatalytic MB removal efficiency was evaluated by the degradation of MB under UV light illumination using a UV–vis spectrometer. The MB removal efficiency of the TiO2 synthesized anatase powder was only 32.3 % whereas, for TiO2 embedded PG (TiPG) it was 91.6 %, and nearly complete (> 99 %) efficacy was achieved for TiO2 embedded alkaline leached PG (TiPG-AL) under UV illumination 3 h period. Better MB removal efficiency was attributed to high SSA and dispersion of nano size anatase TiO2 crystallites within the porous structure. © 2020 Elsevier Ltd